Various embodiments provide for the implementation of volumetric diffractive optics equivalent functionality via cascaded planar elements. To illustrate the principle, a design 3D diffractive optics and implement a two-layer continuous phase-only design on a single spatial light modulator (SLM) with a folded system. The system provides dynamic and efficient multiplexing capability. Numerical and experimental results show this approach improves system performance such as diffraction efficiency, spatial/spectral selectivity, and number of multiplexing functions relative to 2D devices while providing dynamic large space-bandwidth relative to current static volume diffractive optics. The limitations and capabilities of dynamic 3D diffractive optics are discussed.